(19)

(11)

EP 1 018 137 A2

(12)

(88) Date of publication A3: 17.06.1999 (43) Date of publication: 12.07.2000 Bulletin 2000/28 (21) Application number: 98944099.5 (22) Date of filing: 24.09.1998

(51) International Patent Classification (IPC)7: H01J 37/063, H01J 37/065, H01J 37/075, H01J 37/301 (86) International application number: PCT/GB9802/882 (87) International publication number: WO 9916/101 (01.04.1999 Gazette 1999/13)

(84) Designated Contracting States: AT BE CH DE DK ES FI FR GB GR IE IT LI NL PT SE (30) Priority: 24.09.1997 GB 9720350 (71) Applicant: THE WELDING INSTITUTE Great Abington,Cambridge CB1 6AL (GB)	(72) Inventor: SANDERSON, Allan DuxfordCambridgeshire CB2 4QW (GB) (74) Representative: Skone James, Robert Edmund et al GILL JENNINGS & EVERYBroadgate House7 Eldon Street London EC2M 7LH London EC2M 7LH (GB)